Abstract: The transmission line has been operating in the wild for a long time, and the terrain and geology of the area it passes through are constantly changing. Some towers pass through a large number of quarries and soil taking operations, which cause geological settlement and displacement in the transmission line protection area. The foundation of the transmission line also changes, seriously threatening the safety of the transmission line operation. By summarizing the traditional operation methods of geological change measurement in the goaf, the combination method of prism free and reflector free Total station is proposed to track and observe the geological change in the goaf, providing scientific data for the next step of renovation.